There are several reasons that have made wave energy converters more attractive since the beginning of the present decade. First, there are global warming issues—carbon dioxide emissions must be reduced in many industrialized countries due to ratification of the Kyoto Convention, and its future successor being discussed in Copenhagen 2009. Also, recent hurricane seasons have created growing concerns among some industrialized countries about climate change. The Fourth Report of Intergovernmental Panel on Climate Change Convention (IPCCC) release in 2007 has clearly stated that anthropogenic activities are partially responsible for increase emissions of green house gases and the increase in the average global temperatures. Cuts in greenhouse gas emissions may ultimately be needed to stabilize atmospheric concentrations of the gases and avert serious climate disruptions. This reduction in greenhouse gases may require a global transition to renewable energy sources and improvements in energy efficiency.
Secondly, a dwindling supply of peak oil reserves and growing demand of oil by large nations such as China and India, in addition to growing political tensions in oil producing countries, have increased oil prices tremendously. It is expected that during the expected period of maturity of wave technology (2009-2015) and consolidation of its market (up to 2025), the price of oil is projected to be near or above US$ 50 per barrel. This scenario makes the development of alternative energy technology very viable.
Others issues such as declining coal use, increased opposition to hydroelectric dams, increasing demand for renewable energy sources, and deregulation of energy markets may contribute to the development of alternative energy technology, and in particular, ocean and wave energy converters.
The reduction of emissions of green house gases (GHG) and relevance and importance of the introduction and use of renewable energy technologies, especially for clean electric power generation, to contribute to these reductions are by now obvious and need not to be explained more extensively here. Within the new technologies that are being developed in the last few years for clean power generation, those based on marine renewable resources (especially waves) have great potential, due to its concentrated power and high predictability. It is expected that the average growth in electricity generation based on marine renewable resources (wave and tidal) will be around 12% in the period 2007-2015. Realizing this, countries like Ireland and Portugal have developed national strategies for the introduction of marine renewable power and others, like New Zealand and the UK, created funds and other incentives for the same purpose. The US, a latecomer in this sector, has even go further and passed the “Energy Independence and Security Act of 2007” in December 2007 with a specific section (Subtitle C) on Marine and Hydrokinetic research and development. Additionally, in April 2009, the US has taken a major step to boost marine renewable energy by issuing a long-awaited set of rules that will significantly help the development of offshore wave energy along the US coastlines.
Until recently, all wave energy conversion (WEC) technologies were being developed in industrialized countries with high-energy intensity seas (average wave height 2 meters and above) and were conceived to ultimately work in central grid-connected generation wave farms or parks. Developing marine renewable energy technologies in these temperate weather countries has let to conceptualization of technologies with high capital costs per installed kW capacities due to survival features in the designs (Pelamis, for example, one of the most well known offshore wave energy technologies, is designed to survive waves of up to 28 meters high. See, www.Pelamiswave.com, incorporated herein by reference). This has let European groups such as WaveNet, to infer that most of the shoreline/near-shore wave power devices start to become economically competitive at wave power levels of 40 kW/m (i.e., average wave height of three meters @ periods of ten seconds) and above, and that some of the offshore wave power devices also start to become economically competitive at offshore wave power levels of 30 kW/m (i.e., average wave height of. 2.7 meters @ periods of 10 seconds) and above.
Since most developing countries have low energy intensity seas, especially those in the tropical regions, with average wave power levels of 3 to 15 kW/m, the above mentioned issue results in an erroneous tendency within the renewable wave energy technology developers in industrialized countries to believe that the majority tropical countries are not or will not be beneficiaries of this type of technology because of their low energy intensity seas.
Most of the technologies for wave energy conversion that have been developed are based on the extraction of either the potential energy (that generates the up and down movement of water molecules) contained in waves (i.e., heaving buoys, point absorbers) or the kinetic energy (that generates the back and forth movement of water molecules) contained in waves (i.e., oscillating wave surge converters). Very few devices are conceived to extract both the potential energy and kinetic energy of waves.
To be able to work economically in seas of lower energy intensity, wave energy conversion technology needs to be more efficient in the extraction of energy from waves. This requires the development of devices that extract simultaneously both the potential energy and the kinetic energy from waves.
The motion of ocean waves has long been considered a major potential resource of both potential and kinetic energy. At the same time, wave energy performance measures are characterized by diffuse energy, enormous forces during storms, and variation over wide range in wave size, length, period, and direction. Techniques for changing the random forces generated by waves into useful energy in an apparatus may be through one or more of the following power take-off systems, including pneumatic systems, hydraulic systems, piezoelectric systems, electrical systems, and mechanical systems.
These Prior Art systems are not conceptualized to simultaneously extract both the potential energy and the kinetic energy contained in waves. The majority of these systems are design to extract only the potential energy contained in the up and down movement of water molecules in the wave. Very few of the systems are design to extract the kinetic energy derived from the back and forth movement of water molecules in the wave. Also, these Prior Art systems have no self-oriented capability to position themselves to absorb the maximum amount of energy from waves and thus optimize energy production.
The aforementioned problems or challenges are precisely those which the present invention is oriented to solve.